1. Field of the Invention
The present invention relates to an electronic circuit, and more particularly, to a multilevel voltage generator for generating a variety of voltage levels.
2. Description of the Related Art
A liquid crystal display (LCD) device that is a display device among electronic circuit apparatuses displays an image by controlling light transmissivity of liquid crystal using an electric field. To this end, the LCD device includes a liquid crystal panel in which liquid cells are arranged in a matrix format and a driving circuit for driving the liquid crystal panel.
The liquid crystal panel includes a thin film transistor formed at each of cross-points of gate lines and data lines and the liquid crystal cell connected to the thin film transistor. A gate electrode of the thin film transistor is connected to any one of the data lines in units of horizontal lines while a source electrode is connected to any one of the data lines in units of vertical lines. The thin film transistor supplies a pixel voltage signal from the data line to the liquid crystal cell in response to a scan signal from the gate line.
In order to drive the thin film transistor type LCD device (hereinafter, referred to as “TFr-LCD”), a gate drive for driving the gate lines of the thin film transistor and a source driver for driving the source lines of the thin film transistor are provided. The gate driver turns on the thin film transistor by applying a high voltage and the source driver applies an analog pixel signal to indicate color to the source line, so that an image is displayed on the TFT-LCD.
The source driver sequentially latches digital pixel data in response to a Sampling data, converts the latched digital pixel data to an analog pixel signal, and buffers and outputs the analog pixel signal. In particular, the source driver outputs a voltage corresponding to pixel data input of voltages V1-V64 corresponding to all bit combination of, for example, 6 bit pixel data, as a pixel signal. For this operation, the source driver includes blocks which are driven with a power of a variety of voltage levels.
The driving circuits such as the gate driver or the source driver need a variety of voltage levels and a multilevel voltage generator for generating a variety of voltage levels has been widely known. However, in accordance with the miniaturization of electronic circuit apparatuses, a multilevel voltage generator which can generate a variety of voltage levels with a reduced number of constituent elements is required.